shape tech 2

has a seam, it's a cast resin that's been sanded and worked a bit, 2 set screws.
it's indicator is a curved cutout that gives a surprising kind of precision in the suddenness of wiping the graduations. (like how distortion/folder circuits bring out hidden interior aspects of the sounds?)
Research into properties of variations on the curve of the cutout. relationship to lensed skirts I've seen?